A team of researchers from three different universities are collaborating to study how nanoscale crystals self assemble. A team at UPenn, led by Christopher Murray was working on a problem related to “herringbone” patterns that self assemble in flat metallic nanocrystals. Murray turned to Sharon Glotzer, a former colleague from UPenn and now working at the University of Michigan, for assistance. Glotzer’s team was working on computer simulations and built a model capable of recreating the same patterns seen at UPenn. Then Murray asked Ju-Li, another former colleague from UPenn, now a professor of nuclear science at MIT, for help explaining the quantum mechanics of how the chemical chains combined at the edges.

The outcome of the collaboration seems to show that subtle changes in the architecture of the chemical building blocks can have significant effects on the larger self assembling patterns. The final goal of the work is to develop techniques for nanoscale arrangements that produce a variety of complexity and functionality at the macroscale.

When University of Pennsylvania nanoscientists created beautiful, tiled patterns with flat nanocrystals, they were left with a mystery: why did some sets of crystals arrange themselves in an alternating, herringbone style, even though it wasn’t the simplest pattern? To find out, they turned to experts in computer simulation at the University of Michigan and the Massachusetts Institute of Technology.

The result gives nanotechnology researchers a new tool for controlling how objects one-millionth the size of a grain of sand arrange themselves into useful materials, it gives a means to discover the rules for “programming” them into desired configurations.

Ultimately, researchers want to modify patches on nanoparticles in different ways to coax them into more complex patterns. The goal is a method that will allow people to imagine what they would like to do and then design a material with the right properties for the job.

“By engineering interactions at the nanoscale, we can begin to assemble target structures of great complexity and functionality on the macroscale,” said U-M’s Sharon Glotzer, the Stuart W. Churchill Collegiate Professor of Chemical Engineering.

Glotzer introduced the concept of nanoparticle “patchiness” in 2004. Her group uses computer simulations to understand and design the patches.